Photographic lens of high image-resolving power comprising two doublets and four single lens elements

ABSTRACT

A PHOTOGRAPHIC LENS OF HIGH-IMAGE RESOLVING POWER COMPRISES TWO DOUBLETS AND FOUR SINGLE LENS ELEMENTS. IT DEFINES A FIELD ANGLE OF 2$=10* WITH AN APERTURE OF 0.36, AND A FIELD ANGLE OF 2$=14* WITH AN APERTURE OF 0.25. THE IMAGE ERRORS ARE HIGHLY CORRECTED, AND THE WAVE ABERRATION LIES WITHIN THE RAYLEIGH LIMITS. THE LENS MEMBERS, FROM OBJECT SIDE TO IMAGE SIDE, ARE ARRANGED UNDER DEFINITE CONDITIONS AS FOLLOWS: A POSITIVE DOUBLET, AN APERTURE DIAPHRAGM, A POSITIVE MENISCUS, A BICONCAVE ELEMENT, A BICONVEX ELEMENT, A POSITIVE DOUBLET, AND A BICONCAVE ELEMENT.

350-464 SR 7 M 00 OR 3,702,215 SEARCH R ,v Nov. 7, 1972 MAENZ El'AL3,702,216

PHOTOGRAPHIC LENS OF HIGH IMAGE-RESOLVING POWER COMPRISING TWO DOUBLETSAND FOUR SINGLE LENS-ELEMENTS Filed Jan. 29, 1971 lNVENTORS MOM @4404,k.

{Mama "Kb 4 United States Patent Of 3,702,216 PHOTOGRAPHIC LENS OF HIGHIMAGE-RESOLV- ING POWER COMPRISING TWO DOUBLETS AND FOUR SINGLE LENSELEMENTS Harald Maenz, Jena, and Gerhard Risch, Weimar, Germany,assignors to Jenoptik Jena G.m.b.H., Jena,

District of Gera, Germany Filed Jan. 29, 1971, Ser. No. 109,266 Int. Cl.G02b 9/62 US. Cl. 350-215 3 Claims ABSTRACT OF THE DISCLOSURE element, abiconvex element, a positive doublet, and a,

biconcave element.

This invention relates to a photographic lens of high image-resolvingpower of the kind comprising two doublets and four single lens elements,which defines a field angle of 26=10 with an aperture of 0.36 and afield angle of 26=14 with an aperture of 0.25. For the sake of clarity,the doubles are hereinafter designated UK and VI/ VII; and the singleelements, III, IV, V and VIII, counting from front to rear, i.e. fromobject side to image side. The aperture diaphragm lies between thepositive doublet I/II and the positive single element III. The doublet1/11 is biconvex, its cemented face being concave towards the object.The element HI is a positive meniscus having its concave face in therear. The elements IV and VIII are biconcave and include the element Vand the doublet VI/VH the cemented face of which is concave towards theobject. The element V and the doublet VI/VII are biconvex.

The known lenses of the foregoing kind, of large aperture andcomparatively large field angle, have an image-resolving power whichlies far below the theoretical possibility of sin a t wherein a is theangle of aperture and Jr is the wavelength used. However, moderntechnology, for example in making miniature electronic circuits or inthe microrecording of documents, is bound to rely on lenses thatactually ensure the said theoretical image-resolution. The prior artlenses for this particular purpose are either corrected for an aperturesmaller than 0.25 or have a useful field angle that lies below 28:8".

The present invention aims at providing a photographic lens of theforegoing kind by means of which the theorectically possibleimage-resolving power is obtained with an aperture of 0.36 and a fieldangle of 26=10 or with an aperture of 0,25 and a field angle of 26=.14.Moreover, the qualities of very good correction of the geometric-opticalimage errors, such as aperture error, imagefield curvature, astigmatism,sagittal and meridional coma,

distortion, longitudinal and transverse chromatical aberration, are tobe accompanied by a wave aberration that lies within the Rayleighlimits. A criterion of the residual errors of wave aberration is thedefinition brillancy, which must be above percent.

To this end, the present invention consists in a photographic lens ofhigh image-resolving power which comprises, from object side to imageside, a doublet I/II, single lens elements III, IV, V, a doublet VI/VII,and a single lens element VIII, the doublet I/ II and the element IIIbeing positive and including an aperture diaphragm; and in which theelement I is biconvex, the cemented face being concave towards theobject, and the element III is a meniscus having its concave face in therear; and in which the elements IV and VIII are biconcave and includethe element V and the doublet VI/VH, the element V and the doubletVI/VII being biconvex, and the cemented face in VI/VII being concavetowards the object; wherein the sum of the radii of those faces of theelements IV and V which bound the intermediate air space is greater than1.2; and smaller than f being the focal length of the entire lens; thedifference of the refractive indices n of the cemented elements VII andVI, referring to a wavelength )\=546.1 nm., is greater than 0.08 andsmaller than the difference of the Abbe numbers of the cemented elementsVI and VII lies between 20 and the refractive power of VIII is greaterthan l.65;, and smaller than -1.45rp ,(1.65q0 p 1.45 o being therefractive power of the entire lens; the sum of the refractive powers ofVI and VII lies between 0.50) and 0.7(p (0.5tp (Pv +tpvn0.7(p and thesum of the thicknesses of the lens elements I and II is greater than0.5f and smaller than The following Tables 1 and 2 and the FIGS. 1 and 2of the accompanying drawing illustrate two embodiments of the lensaccording to the invention, the scale of the drawing being 50:1.

The lens of Table 1 and FIG. 1 is corrected for an aperture 0.36, animage angle 26=10 and an image scale 18 ='0.1O. The lens of Table 2 andFIG. 2 is corrected for an aperture 0.25, an image angle 26:14 and animage scale fl =-0.l67. The focal length of both lenses is 1.

Patented Nov. 7, 1972 TABLE 2 TABLE 1 Thickness (t) or Thlckness(t) orRadii distanee(5) 715 v5 Radil d1stance(s) 71. vf =1.2l80 5 T1=l.3834

:1=0.4201 1. 68111 55. 2 t =0.4581 1. 52522 66. 4 n 3'0334 t o 1188 11045s 20 8 YFLHW 1 01451 1 7 I: 0451 40.7 n=64.6607 n=28.4096

:09681 (Diaphragm p e) 9002 n=0.0458 (Diaphragm space) t =o.12s5 1.68102 55. 2 68080 ":34137 a: 00636 76:2.8161 1, 0.1714 1. 54.8

O 6851 t1=0.2764 1. 70458 29. 8 t =0 1947 1. 033 33. 2 n- F0 1713r1=o.5219 0 2107 t1=0.2957 1.68111 55.2 595 m 1.680 54.8 n-1.9567 00028n=-2.349s

l 8 =0.0038 m=1.0a39 r10=0.9437

t.=o.a555 1. 57018 55. 7 :,=0.3 1. 59155 52. 9 f1 =0.7585 m=0.4205

z1=0.0533 1. 67765 32. 0 1 1. 8939 30. 9 m= 3.1969 0 1244 m= 4.0303

55= 20 85=0J519 m=-o.5042 m=-0.4541

ta=0.1219 1. 68102 55. 2 t =0 0359 1, 7273 46,7 T14=3.4147 f =19.0911 8wherein r stands for radius, 1 for thickness, s for distance, n forrefractive power, and w for Abbe number.

3. A lens as claimed in claim 1, characterized by the followingfeatures:

TABLE 2 We claim: Thickness (t) or 1. A photographic lens of high imageresolving power Rad! distancem' which comprises, from object side toimage side, a dou- =0 4201 1 68m 55 2 blet I/H, single lens elements HI,IV, V, a doublet VI/ VII, and a single lens element VIII, the doubletI/II and r 6607 3 0458 293 the element III being positive and includingan aperture 35 z s =0.0663 iaphrazmspace) diaphragm; and m which theelement I is biconvex, the FPO-9631 F0128, 1 68102 55 2 cemented facebeing concave towards the object, and the ,11 7 element III is ameniscus having its concave face in the "=4 9550 rear; and in which theelements IV and VIH are bicont =0.2764 1.70458 29.8 cave, and theelement V and the doublet VI/VII are 40 =0 1713 biconvex, the cementedface in VI/VII being concave ,=0.7501 towards the object; wherein thesum of the radii of those 19667 ":02957 L681 faces of the elements IVand V which bound the inter- =0 0Q2g mediate air space is greater than1.2 and smaller than l- :03565 1 57-018 55 7 1.5 (l.2fr +r 1.5f), beingthe focal length of the 4 m=0.7585 entire lens, the difference of therefractive indices n of no m3.1969 the cemented elements VII and VI,referring to a wave- 51=0.1244 length 7\=546.1 nm., is greater than 0.08and smaller :01219 1.68102 5 than 0.12. (0.08n -n 0.12); the differenceof the m=3.4147 Abbe numbers of the cemented elements VI and VII liesbetween 20 and 26 (20v -u 26); the refractive power of VIII is greaterthan 1.65 p and smaller than 1.45q0 (1.65 p p -1.45 (p being therefractive power of the entire lens; the sum of the refractive powers ofVI and VII lies between 0.5 and 0.7 (0.5 p p p 0.7 and the sum of thethicknesses of the lens elements I and II is greater than 0.5) andsmaller than 0.65f (0.5 ft +t 0.65 f).

2. A lens as claimed in claim 1, characterized by the followingfeatures:

wherein r stands for radius, 1 for thickness, s for distance, ri forrefractive power, and 0 for Abbe number.

References Cited UNITED STATES PATENTS 2,989,895 6/1961 Sandback 350-2153,395,962 8/1968 Herzberger et al. 350-215 3,602,578 9/1971 Tibbetts etal. 350-215 JOHN K. CORBIN, Primary Examiner

